okeson chapter

1. Functional neuroanatomy and
physiology of masticatory system
Preeti Kalia
3rd year PG student
Department of Prosthodontics
AECS Maaruti College of Dental
Sciences

2.  “You cannot successfully treat dysfunction
unless you understand function”

3. Functional
neuroanatomy
and physiology
of masticatory
system
Neuromuscular
system
Muscle Nerve
Neuromusc
ular
function
Pain

4. Neuromuscular
system
Neurological Muscles
structure

5. Muscles

6. Muscle function
 Isotonic contraction
 Isometric contraction
 Relaxation

7. Muscle function

8. Muscle function
 Eccentric contraction

9. Neurological structure

10. Types of neurons
 Afferent neurons
 Efferent neurons

11. Reticular formation

12. Thalamus

13. Hypothalamus

14. Limbic structure

15. Cerebral cortex

16. Sensory receptors
 Nociceptors
 Propriceptors
 Muscle spindle
 Golgi organ
 Pacinian corpuscle

17. Muscle spindles

18. Golgi tendon receptor

19. Pacinian corpuscles

20. Nociceptors

21. Neuromuscular function
Reflex action:
It is response resulting from a stimulus that passes
as an impulse along afferent neurons to a
posterior nerve root or its cranial equivalent

22.  Monosynaptic reflex
 Polysynaptic reflex

23. Myotatic reflex

24. Nociceptive reflex
 It is a polysynaptic reflex
 Seen when hard food substances are taken in the
mouth

25. Reciprocal innervation
 The controlling mechanism of antagonistic group of
muscles

26. Regulation of muscle activity
 Gamma charge keeps the alpha motor neuron reflex
prepared to receive impulses
 Influence of higher centers

27. Major function of masticatory
system
Mastication
Swallowing Speech

28. Mastication
 Defined as act of chewing food

29. Chewing cycle

33. Mascles activity

34. Opening
 Start from static intercuspal
position
 muscle activity begins in the
ipsilateral inferior head of the
lateral pterygoid muscle
approximately half way through
the period of tooth contact.
 Follow closely by the action of
the contralateral inferior lateral
pterygoid muscles.
 Both superior and inferior head
of th lateral pterygoid muscle
are active during the opening
phase.

35. Opening
 Early in the opening phase,
digastric muscles become active and remain until
maximum opening position
 During the opening phase,
masseter, temporalis, medial
pterygoid, and superior head of lateral
pterygoid muscles are
inactive.

36. Closing
 initiation of jaw closing
the inferior heads of the lateral pterygoid muscle
ceases their functioning and activity
 initiated in the contralateral medial pterygoid
muscle

37. Closing
 Contralateral medial pterygoid controls the upward and
lateral positions of the mandible
 Activity increases in the anterior and posterior temporalis
muscle, in the deep and superficial masseter muscles,
and in the ipsilateral medial pterygoid muscle
 anterior and posterior temporalis muscle, in the deep
and superficial masseter muscles, and in the ipsilateral
medial pterygoid muscle activity declines in activity at
the onset of intercuspation.
 There appears to be reciprocal action between the
inferior head of the lateral pterygoid muscle and the
medial pterygoid muscle in same subject

38. Tooth contact during mastication
 Gliding contacts
 Single contact
 Average time for tooth contact is 194 minutes
 60% Gliding contacts seen during grinding
 56% gliding contacts seen during opening

39. Forces of mastication
 Maximum biting force in females 70 to 99 pounds
 Males 118 to 142 pounds
 Maximum bite force for molar 91 to 198 pounds
 Central incisors 29 to 51 pounds

40. Swallowing
 Series of coordinated muscle movements that
moves bolus from oral cavity through esophagus to
stomach

41.  Somatic swallow
 Visceral swallow

42. Stages

43. Frequency of swallowing
 590 times in 24 hours
 146 cycles during eating
 394 in between meals
 50 cycles during sleep

44. Speech
 Important sounds formed by the lip are m,band p
 Teeth are important in saying s
 Tongue and palate are essential in forming d
 Tongue touches maxillary incisors to form th
 Lower lip touches maxillary incisors to form f and v

45. Pain
 Unpleasant sensation perceived in the cortex as a
result of incoming nociceptive input.

46. Modulation of pain
 Non painful cutaneous nerve stimulation
 Intermittent painful stimulation
 Psychological modulation

47. Types of pain
 Central pain
 Projected pain
 Referred pain

48. Central excitatory effect
 Explains the mechanism of referred pain

49.  “Pain is inevitable. Suffering is optional.

50. References
 Okeson.J.P, Temporomandibular disorders and
occlusion,6th edition , 2008, Mosby publication, St
Louis, United States of America, pp:25-57